Display device and sputtering target for producing the same

ABSTRACT

A display device in which an Al alloy film and a conductive oxide film are directly connected without interposition of refractory metal and some or all of Al alloy components deposit or are concentrated at the interface of contact between the Al alloy film and the conductive oxide film. The Al alloy film contains 0.1 to 6 at % of at least one element selected from the group consisting of Ni, Ag, Zn, Cu and Ge, and further contains 1) 0.1 to 2 at % of at least one element selected from the group consisting of Mg, Cr, Mn, Ru, Rh, Pd, Ir, Pt, La, Ce, Pr, Gd, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu and Dy or 2) 0.1 to 1 at % of at least one element selected from the group consisting of Ti, V, Zr, Nb, Mo, Hf, Ta and W, as the alloy components.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device shaped like a thinfilm and a sputtering target for producing the same, and moreparticularly, to a novel display device including an oxide conductivefilm and an Al alloy film and for use in semiconductor devices, flatpanel displays of the active and the passive matrix types such as liquidcrystal displays, reflection films, optical components and the like andto a sputtering target for producing the same.

2. Description of the Related Art

Thin film transistors (TFTs) serve as switching elements in a liquidcrystal display of the active matrix type for instance, and the liquidcrystal display has a TFT array substrate including pixel electrodes andinterconnection portions such as scanning lines and signal lines, anopposed substrate which includes a common electrode and is disposed overa predetermined distance facing the TFT array substrate, and a liquidcrystal layer which is injected between the TFT array substrate and theopposed substrate. A liquid crystal display of the passive matrix typeincludes interconnection portions such as scanning lines and signallines, an opposed substrate which includes a common electrode and isdisposed over a predetermined distance facing this interconnectionsubstrate, and a liquid crystal layer which is injected between theinterconnection substrate and the opposed substrate. The pixelelectrodes may be made of an oxide conductive film such as an indium tinoxide (ITO) film which is obtained by mixing about 10 mass % of tinoxide (SnO) in indium oxide (In₂O₃).

While pure Al or Al alloy such as Al—Nd is used for the signal lines ofthe interconnection portions electrically connected with the pixelelectrode of such a conductive oxide film (hereinafter also referred as“pixel electrodes”), a multi-layer film made of refractory metal, suchas Mo, Cr, Ti and W, is interposed as barrier metal between the signallines and the pixel electrodes so that the signal lines will notdirectly contact the pixel electrodes. However, the recent years haveseen an attempt for omission of such refractory metal and directconnection of the pixel electrodes with the signal lines.

According to Patent Document 1 (JP, 11-337976, A) for instance, use ofpixel electrode of an IZO film obtained by mixing about 10 mass % ofzinc oxide in indium oxide realizes direct contact with signal lines.

Patent Document 2 (JP, 11-283934, A) describes a surface treatmentmethod by means of plasma processing, ion implantation or the like of adrain electrode, while Patent Document 3 (JP, 11-284195, A) describes amethod of forming, as a gate, a source and a drain electrodes of a firstlayer, a multi-layer film in which a second phase containing impuritiessuch as N, O, Si, C or the like is stacked. Where these methods areused, clearly, it is possible to maintain the contact resistance withpixel electrodes at a low level even when such refractory metal as thatdescribed above is omitted.

The reason of interposing barrier metal according to these conventionaltechniques is because direct contact between interconnections of Al orAl alloy forming signal lines and pixel electrodes increases the contactresistance and degrades the quality of a displayed image. This isbecause Al easily gets oxidized and its surface gets oxidized in theatmosphere, and because pixel electrodes which are metal oxides seat intheir surfaces a high-resistance Al oxide layer as Al is oxidized byoxygen which is created or added during film deposition. Forming of theinsulation layer at the interface of contact between the signal linesand the pixel electrodes increases the contact resistance between thesignal lines and the pixel electrodes and deteriorates the quality of adisplayed image.

Meanwhile, although barrier metal has a function of preventing oxidationof the surface of Al alloy and keeping an Al alloy film and a pixelelectrode in favorable contact, since a barrier metal forming step isindispensable to fabrication of a conventional structure in whichbarrier metal is interposed at this contact interface, it is necessaryto secure a film deposition chamber for forming barrier metal inaddition to a film deposition sputtering apparatus for forming a gateelectrode, a source electrode and further a drain electrode.Nevertheless, as mass production of liquid crystal panels has realized alow cost, an increase of the manufacturing cost and a drop inproductivity due to creation of barrier metal are becoming significant.

Against this background, an electrode material, a manufacturing processand the like for omission of barrier metal are recently demanded. Inresponse, Patent Document 2 proposes addition of one surface treatmentstep. Meanwhile, permitting continuous film deposition of a gateelectrode, a source electrode or a drain electrode within the same filmdeposition chamber, Patent Document 3 inevitably demands more processingsteps. Further, due to different coefficients of thermal expansionbetween a film which contains impurities and a film which is free fromimpurities, the phenomenon that a film falls off from a wall surface ofthe chamber during continuous use is rampant, and therefore, it isnecessary to often stop an apparatus for the purpose of maintenance. Inaddition, since Patent Document 1 requires changing an indium tin oxide(ITO) film which is currently most popular to an indium zinc oxide (IZO)film, the material cost is expensive.

Noting this, the inventors developed the technique described in PatentDocument 4 (JP, 2004-214606, A) as a result of extensive research andstudy in an attempt to establish such a technique with which it ispossible to simplify processing steps while omitting such barrier metalas that described above without increasing the number of the processingsteps and with which it is possible to obtain excellent electricalcharacteristics and heat resisting property which realize a low contactresistance at a low electrical resistivity without fail and achievestandardization of the material with a reflection electrode, a TABconnection electrode and the like in a display device.

This technique is an attempt to solve the problem described above byusing, as the material of an Al alloy film, Al alloy which contains 0.1through 6 at % of at least one element selected from group of Au, Ag,Zn, Cu, Ni, Sr, Sm, Ge and Bi and making a part of these alloycomponents appear as a deposit or concentrated layer at the contactinterface mentioned above, and it has been confirmed that among theseelements, Al alloy containing a predetermined amount of Ni exhibitsexcellent capabilities.

By the way, a process temperature for producing a display devicerecently tends to become low for a better yield and an improvedproductivity, and for further, there are ongoing endeavors to use aresin having a low heat resisting temperature as a base material. Hence,while a demand for a heat resisting temperature is not very strong,there is a significant demand for an interconnection material having alow electrical resistivity.

The material of source and drain electrodes of amorphous silicon TFTs,one type of display device elements, for instance is required to have alow electrical resistivity and a heat resisting property, and demandedspecifications are for example an electrical resistivity of 8 μΩ·cm orlower and a heat resisting temperature of about 350 degrees Celsius.This heat resisting temperature is determined by a maximum temperatureapplied upon the source and drain electrodes during producing, and thismaximum temperature is a temperature of forming an insulation film whichis to be formed as a protection film on the electrodes.

It has become possible to obtain a desired insulation film even at a lowtemperature owing to advanced film deposition techniques, and it isbecoming possible to form a protection film in particular on source anddrain electrodes at about 250 degrees Celsius. This gives rise to ademand for an interconnection material whose heat resisting temperatureis approximately 250 degrees Celsius and whose electrical resistivity issufficiently low.

Meanwhile, although an Al alloy film generally used from before as aninterconnection material for a display device is formed by sputtering,in the case of an Al alloy film formed by this method, alloy componentsadded beyond a solubility limit to Al is compelled to exist in thedissolved state. The electrical resistivity of Al alloy containing analloy element in the dissolved state is generally higher than that ofpure Al. However, when an Al alloy film containing an alloy elementbeyond a solubility limit is heated, alloy components precipitate at thegrain boundaries as an intermetallic compound, and as the Al alloy filmis further heated, grain growth advances and Al starts re-crystallizing.While the temperature at which the precipitation and the grain growthoccur in this manner is different depending upon the alloy element, theprecipitation and the grain growth of the alloy components decrease theelectrical resistivity of the Al alloy film.

The compressive stress inside the film increases as the grain growthprogresses due to heating, and as the grain growth further progressesdue to further heating, the limit will be surpassed and crystal grainswill appear to the film surface as hillocks for the sake of stressrelaxation. Alloying is effective in holding grains in a halt by meansof the intermetallic compound precipitating at the grain boundaries,suppressing hillocks and enhancing the heat resisting property. Aconventional approach has been to advance precipitation and grain growthof alloy components utilizing this phenomenon for realization of both alower electrical resistivity and a heat resisting property of an Alalloy film. However, a lowered process temperature does not encouragesufficient precipitation of conventional alloy components as anintermetallic compound, which leads to a problem that grain growth doesnot advance and an electrical resistivity does not easily decrease.

For example, although the heat resisting temperature of Al-2 at % Nddisclosed in Patent Document 4 is as high as 350 degrees Celsius ormore, the electrical resistivity is only 11.5 μΩ·cm after heat treatmentat 250 degrees Celsius for 30 minutes, and although the heat resistingtemperature of Al-2 at % Ni-0.6% Nd is as high as 350 degrees Celsius ormore, the electrical resistivity decreases down to only 8.7 μΩ·cm afterheat treatment at 250 degrees Celsius for 30 minutes, thus still leavinga room for further improvement.

SUMMARY OF THE INVENTION

As described above, although source and drain electrodes are mostinfluenced by a lowered process temperature, since these electrodesalways carry a current to read from and write in pixels, to suppress theelectrical resistivity in these electrode portions is extremelyeffective in reducing the power consumption of a display device.Further, the low electrical resistivity in the electrode portions lowersa time constant which is determined by the product of the electricalresistance and the electrical capacity, which makes it possible tomaintain a good display quality even when a display panel is to befabricated in a large size.

The present invention has been made in light of the circumstance above,and accordingly, aims at establishing a technique with which it ispossible, on the assumption that omission of barrier metal addressedabove in relation to the conventional techniques is possible, todirectly and securely contact an Al alloy film with pixel electrodes andachieve a low electrical resistivity between the pixel electrodes evenwhen a low thermal processing temperature is used for the Al alloy film.More specifically, even when thermal processing at as low temperature as250 degrees Celsius for 30 minutes is performed, it is possible toachieve the electrical resistivity of 7 μΩ·cm or lower of the Al alloyfilm without creating defects such as hillocks, provide a display devicewhich is adaptive to a lowered processing temperature and provide asputtering target for creation of Al alloy film which is useful forproducing such a display device.

In the structure of a display device according to the present inventionwhich solves the problems above, an Al alloy film and a conductive oxidefilm are connected directly with each other without any interposedrefractory metal, and in this display device, at this contact interface,some or all Al alloy components precipitate or is concentrated, and theAl alloy film is made of Al alloy which contains as the alloy components0.1 through 6 at % of at least one element selected from the groupconsisting of Ni, Ag, Zn, Cu and Ge and which further contains 1) 0.1through 2 at % of at least one element selected from the group(hereinafter sometimes referred to as “group X”) consisting of Mg, Cr,Mn, Ru, Rh, Pd, Ir, Pt, La, Ce, Pr, Gd, Tb, Sm, Eu, Ho, Er, Tm, Yb, Luand Dy or 2) 0.1 through 1 at % of at least one element selected fromthe group (hereinafter also referred to as “group Z”) consisting of Ti,V, Zr, Nb, Mo, Hf, Ta and W.

The Al alloy film according to the present invention, after deposited ona transparent substrate, preferably has an electrical resistivity of 7μΩ·cm or lower following thermal processing at 250 degrees Celsius for30 minutes.

The other structure according to the present invention is directed to asputtering target for producing an Al alloy film which is acharacteristic element of the display device above, and is made of Alalloy which contains, as alloy components, 0.1 through 6 at % of atleast one element selected from the group consisting of Ni, Ag, Zn, Cuand Ge, and further contains 0.1 through 2 at % of at least one type ofelement selected from the group consisting of Mg, Cr, Mn, Ru, Rh, Pd,Ir, Pt, La, Ce, Pr, Gd, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu and Dy or 0.1through 1 at % of at least one element selected from the groupconsisting of Ti, V, Zr, Nb, Mo, Hf, Ta and W.

According to the present invention, it is possible to contact an Alalloy film with pixel electrodes directly without forming a barriermetal layer and secure a sufficiently low electrical resistivity evenwhen a relatively low thermal processing temperature such as 250 degreesCelsius or lower is used. The thermal processing temperature in thiscontext means a processing temperature which becomes the highest duringproducing a TFT array for instance, and examples of this temperature forheating a substrate during film deposition by means of CVD to formvarious types of films, the temperature of a heat treat furnace duringheat curing of a protection film, etc.

When the Al alloy film according to the present invention is applied tosource/drain interconnections during producing a liquid crystal displaypanel in which a process temperature is recently becoming lower, it ispossible to attain a low electrical resistivity at a low thermalprocessing temperature without impairing the advantage of the directconnection with the pixel electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explanatory view of an enlarged cross sectionalsurface of exemplary structures of a liquid crystal panel substrate anda liquid crystal display device to which a display device arraysubstrate according to the present invention is applied;

FIG. 2 is a schematic explanatory view of a cross sectional surface ofan exemplary structure of a thin film transistor which is used in thedisplay device array substrate according to the first embodiment of thepresent invention;

FIG. 3 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 2;

FIG. 4 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 2;

FIG. 5 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 2;

FIG. 6 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 2;

FIG. 7 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 2;

FIG. 8 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 2;

FIG. 9 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 2;

FIG. 10 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 2;

FIG. 11 shows a temperature-stress curve on an Al alloy film;

FIG. 12 is a schematic explanatory view of a cross sectional surface ofan exemplary structure of a thin film transistor which is used in adisplay device array substrate according to other embodiment of thepresent invention;

FIG. 13 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 12;

FIG. 14 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 12;

FIG. 15 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 12;

FIG. 16 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 12;

FIG. 17 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 12;

FIG. 18 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 12;

FIG. 19 is an explanatory diagram which shows in order an example ofsteps for producing the display device array substrate shown in FIG. 12;and

FIG. 20 is a drawing which shows a Kelvin pattern used for measurementof the contact resistance between an Al alloy film and a transparentconductive oxide film.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, for contact of the pixel electrodesand the Al alloy film, the Al alloy film contains, as its alloycomponents, 0.1 through 6 at % of at least one element selected from thegroup consisting of Ni, Ag, Zn, Cu and Ge, and further contains 0.1through 2 at % of at least one element selected from the group X or 0.1through 1 at % of at least one element selected from the group Z.

As the Al alloy film contains 0.1 through 6 at % of Ni or the Like, andfurther contains 0.1 through 2 at % of at least one element selectedfrom the group X or 0.1 through 1 at % of at least one element selectedfrom the group Z, at a relatively low thermal processing temperature,precipitates or Ni or the like concentrated layer are formed at thecontact interface with the pixel electrodes, which decreases the contactresistance.

Further, as described in detail later, precipitation as metalliccompounds of elements belonging to these groups X and Z added mainly forimprovement of the heat resisting property facilitates recrystallizationof Al, reduces the electrical resistance of the Al alloy film itself andgreatly decreases the electrical resistance as a whole including thecontact surface.

Meanwhile, when containing 0.1 through 6 at % of Ni or the like andfurther containing 0.1 through 2 at % of at least one element selectedfrom among Mg, La, Mn, Gd, Ta, Dy and Tb out of the elements selectedfrom the groups X and Z or 0.1 through 1 at % of V, the Al alloy film iseffective in remarkably improving the resistance against an alkalinedeveloping solution.

During producing a display device, an interconnection pattern is formedat a step called photolithography. That is, a photosensitive resin(photoresist) is exposed with an UV light source and developed with analkaline developing solution, and an interconnection pattern is formedof a resin. Following this, using the resin as a mask, an Al alloy filmis etched, thereby obtaining an interconnection. At the stage of thisdevelopment, the surface of the Al alloy film is exposed to the alkalinedeveloping solution. A generally used developing solution contains 2.38wt % of TMAH (tetramethyl ammonium hydroxide), and when the Al alloyfilm containing 0.1 through 6 at % of Ni is exposed to this developingsolution, etching progresses at the speed of 80 through 120 nm/min.

On the contrary, in the case of Al alloy films to which Mg, La, Mn, V,Gd, Ta, Dy and Tb are added from the groups X and Z, the etching speedis suppressed down to 10 through 40 nm/min. Noting that the etchingspeed of pure Al in conventional use is 20 nm/min, empirically speaking,approximately double this speed will not cause a problem of filmthinning.

Further, the developing time varies depending upon resins, exposureconditions and the like, and since the time that the surface of the Alalloy film is exposed to the developing solution is about some dozens ofseconds or maximum within one minute and the film thickness of aninterconnection is generally around 100 through 400 nm, ifetching-induced slowing down of the etching speed approximately down tohalf or slower not only prevents elimination of the Al alloy film at thephotolithographic step but obviates film thinning to quite a sufficientextent. This achieves precise processing of the interconnection pattern.

Rework, or redo of the photolithographic step is often executed. Thismeans stripping of a photoresist and redo of the photolithographic steponce again upon occurrence of an abnormal pattern or the like, andsuppressed film thinning promises an advantage that rework can be donemore than once.

It is therefore possible to significantly reduce the number of processsteps and a manufacturing cost while maintaining the display quality ofa display device such as a liquid crystal display at a high level.

While embodiments of the display device according to the presentinvention will now be described in detail with reference to theassociated drawings, the present invention is not limited to theillustrated examples but may be implemented with appropriatemodification to the extent meeting the intentions mentioned earlier anddescribed below. Those modifications all fall within the technical scopeof the invention.

Further, although the Al alloy film according to the present inventionis applicable also to a display device of the passive matrix type whichdoes not include thin film transistors, a reflection electrode of areflection-type liquid crystal display device or the like, a gateelectrode of an amorphous silicon TFT, and a TAB connection electrodefor input/output of a signal to outside without forming a barrier metallayer between the TAB connection electrode and a TAB electrode, suchembodiments will not be described.

FIG. 1 is a schematic explanatory view of an enlarged cross sectionalsurface of the structure of a liquid crystal panel which is mounted to aliquid crystal display apparatus to which the present invention isapplied.

The liquid crystal panel shown in FIG. 1 includes a TFT array substrate1, an opposed substrate 2 which is disposed facing the TFT arraysubstrate 1, and a liquid crystal layer 3 which is disposed between theTFT array substrate 1 and the opposed substrate 2 and functions as alight modulation layer. The TFT array substrate 1 is formed by thin filmtransistors (TFTs) 4 arranged on an insulating transparent substrate(glass substrate) 1 a, pixel electrodes 5 and interconnection portions 6including scanning lines, signal lines, etc.

The opposed substrate 2 includes a common electrode 7 formed entirely onits surface which is on the TFT array substrate 1 side, a color filter 8which is disposed at a position opposed against the pixel electrodes 5,and a light shielding film 9 which is disposed at a position opposedagainst the thin film transistors (TFTs) 4 on the TFT array substrate 1and the interconnection portions 6.

Polarizer plates 10 and 10 are disposed on the outer surfaces of theinsulating substrate forming the TFT array substrate 1 and the opposedsubstrate 2, and the opposed substrate 2 seats an orientation film 11which aligns liquid crystal molecules of the liquid crystal layer 3along a predetermined direction.

In the liquid crystal panel having this structure, an electric fielddeveloping between the opposed substrate 2 and the pixel electrodes 5controls the direction of the orientation of the liquid crystalmolecules within the liquid crystal layer 3 and modulates light which istransmitted by the liquid crystal layer 3 which is disposed between theTFT array substrate 1 and the opposed substrate 2, whereby the amount oflight which is transmitted by the opposed substrate 2 is controlled andan image is displayed.

Further, the TFT array is driven by a driver circuit 13 and a controlcircuit 14, owing to a TAB tape 12 which is lead to outside the TFTarray.

In FIG. 1, denoted at 15 is a spacer, denoted at 16 is a seal material,denoted at 17 is a protection film, denoted at 18 is a diffusion plate,denoted at 19 is a prism sheet, denoted at 20 is a light guide plate,denoted at 21 is a reflection plate, denoted at 22 is a back light,denoted at 23 is a holding frame, and denoted at 24 is a printed circuitboard, which will be described later.

FIG. 2 is a schematic explanatory view of an enlarged cross sectionalsurface of the structure of a thin film transistor portion according tothe first embodiment which is applied to the array substrate of thepresent invention. As shown in FIG. 2, a scanning line 25 is formed byan Al alloy film on the transparent substrate 1 a, and a part of thescanning line 25 functions as a gate electrode 26 which controls turningon and off the thin film transistor. A signal line is formed by an Alalloy film such that the signal line intersects the scanning line 25 viaa gate insulating film 27, and a part of the signal line functions as asource electrode 28 of the thin film transistor. This type is generallycalled the bottom gate type.

In a pixel region on the gate insulating film 27, there is the pixelelectrode 5 of an ITO film which is obtained by mixing SnO with In₂O₃for instance. A drain electrode 29 of the thin film transistor formed byan Al alloy film is electrically connected as a direct contact with thepixel electrode 5.

When a gate voltage is supplied to the gate electrode 26 via thescanning line 25 on the TFT array substrate 1, the thin film transistorturns on, and a drive voltage supplied in advance to the signal linereaches the pixel electrode 5 from the source electrode 28 via the drainelectrode 29. As the drive voltage of a predetermined level is suppliedto the pixel electrode 5, a potential difference is created from theopposed substrate 2 as described in relation to FIG. 1, the liquidcrystal molecules contained in the liquid crystal layer 3 are alignedand light is modulated.

A method of producing the TFT array substrate 1 shown in FIG. 2 will nowbe described briefly. As the thin film transistor formed as a switchingelement, an amorphous silicon TFT using amorphous silicon hydride as asemiconductor layer will be described as an example.

FIGS. 3 through 10 will be referred to for describing one example ofsteps of producing the TFT array substrate 1.

First, by sputtering or the like, an Al alloy film is formed into thefilm thickness of about 200 nm on the glass substrate (transparentsubstrate) 1 a, and the Al alloy film is patterned, thereby forming thegate electrode 26 and the scanning line 25 (FIG. 3). At this stage, itis desirable to etch the rim of the Al alloy film tapered at about 30through 40 degrees so that the coverage of the gate insulating film 27described later would be favorable. Next, as shown in FIG. 4, by plasmaCVD or the like, the gate insulating film 27 is formed by a siliconoxide film (SiOx) whose film thickness is about 300 nm for instance, andan amorphous silicon hydride film (a-Si:H) whose film thickness is about500 nm and a silicon nitride film (SiNx) whose film thickness is about300 nm are formed for instance.

This is followed by patterning of the silicon nitride film (SiNx) asshown in FIG. 5 by back surface exposure using the gate electrode 26 asa mask, thereby forming a channel protection film. After further formingan n⁺ amorphous silicon hydride film (n⁺a-Si:H) doped with phosphoruswhose film thickness is about 50 nm for instance on this, the amorphoussilicon hydride film (a-Si:H) and the n⁺ amorphous silicon hydride film(n⁺a-Si:H) are patterned as shown in FIG. 6.

An Al alloy film whose film thickness is about 300 nm for example isthen formed on this, and through patterning as shown in FIG. 7, thesource electrode 28 integrated with the signal line and the drainelectrode 29 to be brought into contact with the pixel electrode 5 areformed. Using the source electrode 28 and the drain electrode 29 as amask, the n⁺ amorphous silicon hydride film (n⁺a-Si:H) on the channelprotection film (SiNx) is then removed.

As shown in FIG. 8, using a plasma CVD apparatus or the like forinstance, a silicon nitride film 30 is deposited into the film thicknessof about 300 nm for example, thereby obtaining a protection film. Thefilm deposition is performed at about 250 degrees Celsius for instance.After forming a photoresist layer 31 on this silicon nitride film 30,the silicon nitride film 30 is patterned, and a contact hole 32 isformed in the silicon nitride film 30 by dry etching or the like forinstance. Further, although not shown in the drawings, at the same time,a contact hole is formed in a TAB connection section on the gateelectrode at an edge portion of the panel.

Further, after ashing with oxygen plasma for instance as shown in FIG.9, the photoresist layer 31 is stripped using a stripper solutioncontaining amine or the like for instance, and at last, within aretention time of about eight hours for example, an ITO film whose filmthickness is about 40 nm for instance is formed as shown in FIG. 10, andthe pixel electrode 5 is obtained by patterning. At the same time, theITO film is patterned for bonding with TAB in the TAB connection sectionof the gate electrode at the edge portion of the panel, which completesthe TFT array substrate 1.

In the TFT array substrate fabricated by the method above, the drainelectrode 29 of Al alloy and the pixel electrode 5 directly contact eachother and the gate electrode 26 and the ITO film for TAB connectiondirectly contact each other.

At this stage, as the material of the Al alloy film forming the drainelectrode 29 for instance, Al—Ni alloy or alloy of Al and at least oneelement selected from the group consisting of Au, Ag, Zn, Cu, Sr, Sm, Geand Bi may be used and a condition for forming the drain electrode 29may be properly controlled, which still meaningfully reduces the contactresistance between the Al alloy film forming the drain electrode 29 andthe pixel electrode 5, as Patent Literature 4 has clarified.

With respect to alloy containing Al—Ni for instance, after processing atthe temperature of 250 degrees Celsius for 30 minutes, the electricalresistivity is 3.8 μΩ·cm in the case of Al-2 at % Ni, 5.8 μΩ·cm in thecase of Al-4 at % Ni and 6.5 μΩ·cm in the case of Al-6 at % Ni, whichmeans that an alloy film containing Al—Ni will well achieve a targetvalue for a low electrical resistivity.

However, the heat resisting temperature of such Al—Ni alloy is as low as150 through 200 degrees Celsius. When used for a source electrode or adrain electrode of an ordinary display device, noting that the maximumheating temperature is about 250 degrees Celsius, such Al—Ni alloy willbe insufficient in terms of heat resisting property and is notpractical.

As for Al alloy made of Al and at least one element selected from thegroup consisting of Ni, Ag, Zn, Cu and Ge, further study was done fromthe standpoints of both the type of the third component element and thequantity to add, in an effort to clarify alloy which will exhibit anelectrical resistivity of 7 μΩ·cm or lower after thermal processingwhile securing a heat resisting property on the order of 250 degreesCelsius.

In consequence, it was found that mixing of the elements belonging tothe groups X and Z described earlier in predetermined amounts from amonga countless number of elements would form Al multi-component alloy whichwould exhibit an electrical resistivity of 7 μΩ·cm or lower afterthermal processing while securing a heat resisting property which wouldnot create hillocks or the like even in the presence of heat at about250 degrees Celsius.

The elements belonging to the group X may be Mg, Cr, Mn, Ru, Rh, Pd, Ir,Pt, La, Ce, Pr, Gd, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu and Dy, from whichone or two types may be used. For effective exhibition of an improvedheat resisting property and a reduced electrical resistivity due toaddition of these alloy elements, the amounts of the added elementsneeds be from 0.1 through 2 at %. Meanwhile, the elements belonging tothe group Z may be Ti, V, Zr, Nb, Mo, Hf, Ta and W, from which one ortwo types may be used. For effective exhibition of an improved heatresisting property and a reduced electrical resistivity due to additionof these alloy elements, the amounts of the added elements needs be from0.1 through 1 at %.

Any element belonging to any one of the groups X and Z, if added in theamount below 0.1 at %, will not achieve the level of the heat resistingproperty intended in the present invention, whereas when the content ofthe elements belonging to the group X exceeds 2 at % and the content ofthe elements belonging to the group Z exceeds 1 at %, the effect ofreducing the electrical resistivity of the film material will beinsufficient although the heat resisting property will improve more thanneeded. Considering both the heat resisting property and the loweredelectrical resistivity of the film material, a preferable amount to addis from 0.3 at % to 1.8 at % as for the elements belonging to the groupX and from 0.2 at % to 0.8 at % as for the elements belonging to thegroup Z. The content of each element in the case of adding two or moreelements may be determined with reference to the total content.

As shown in Table 1 which will be described later, the elementsbelonging to the groups X and Z are selected based on examples regardingheat resisting properties and the effect of reducing the electricalresistivities which were confirmed through experiments, the criteria forselection can be explained with reference to the temperature-stresscurve on an Al alloy film shown in FIG. 11.

That is, in FIG. 11, the symbol A denotes pure Al, the symbol B denotesAl alloy to which the element belonging to the group X is added, and thesymbol C denotes Al alloy to which the element belonging to the group Zis added.

The Al alloy film B to which the element belonging to the group X isadded exhibits greater compressive stress with an increase of thetemperature. Although grain growth is suppressed during the initialstage of the temperature increase, grain growth starts at a relativelylow temperature and stress relaxation occurs abruptly within a narrowtemperature range. It is considered that the dissolved element presentin this alloy deposits as an intermetallic compound within a shortperiod of time at this stage and that grain growth of Al advances andthe electrical resistivity drops in accordance with the deposition.Namely, the electrical resistivity is sufficiently lowered at arelatively low heating temperature. On the other hand, further heatingwith complete stress relaxation pushes out crystal grains due tocompressive stress developing inside the thin film and easily results increation of hillocks or the like. The heat resisting temperature of thisalloy is considered to be around a temperature of stress relaxation.

On the other hand, the Al alloy film to which the element belonging tothe group Z is added similarly exhibits greater compressive stress withan increase of the temperature, and grain growth of Al starts in asimilar temperature range. However, the elements belonging to the groupZ is diffused from the dissolved state and precipitate as intermetalliccompounds at a relatively slow speed, the intermetallic compoundsprecipitate gradually within a wide temperature range, and stressrelaxation occurs gradually as the precipitation takes place. Ittherefore takes significant heating and a considerably long time untilstress relaxation occurs sufficiently, the dissolved elements almostentirely precipitate as intermetallic compounds while grain growth of Alprogresses and the electrical resistivity of the mother material of thefilm become low enough, for which amount the heat resisting propertyenhances. In short, as compared with the elements belonging to the groupX, the elements belonging to the group Z are more effective in improvingthe heat resisting property as they more slowly deposit as intermetalliccompounds, and thus, it is possible to sufficiently improve the heatresisting property even when the amount of adding these elements issuppressed relatively small.

While the electrical resistivity is dependent also upon the amount ofadding the alloy elements, the elements belonging to the group Z, whenadded in smaller amounts than the elements belonging to the group X are,reduce the electrical resistivity even at a relatively low heatingtemperature as clarified later in relation to an example (Table 1).

Further, the elements belonging to the group Z, although can not beadded in such large amounts as the amounts of adding the elementsbelonging to the group X, are characterized in that they are unlikely tohave voids (holes) when deposited as electrode films. In other words,when an element which precipitates as an intermetallic compound all atonce within a narrow temperature range during heating is chosen likethose elements belonging to the group X, the more grain growth advances,the stronger the tensile stress created inside the film becomes duringcooling down to a room temperature after heating, which could createvoids. However, in the case of alloy from which an intermetalliccompound precipitates gradually over time in accordance with atemperature increase like the elements belonging to the group Z, sinceprecipitation and grain growth are interrupted upon heating to the sametemperature range as that for the group X, stress relaxation does notprogress sufficiently, and therefore, the tensile stress which remainsin the film decreases during subsequent cooling down to a roomtemperature. Considering this, for prevention of voids attributable tothe tensile stress, it is desirable to select the elements belonging tothe group Z.

The reason that the content of Ni or the like, which serves as the baseof added alloy, is set to the range from 0.1 to 6 at % in the presentinvention is because this is an important requirement to secure the heatresisting property of the Al alloy film, form an Ni or the likeconcentrated layer at the contact interface with the pixel electrodes,and reduce the contact resistance with the pixel electrodes. If thecontent of Ni or the like is below 0.1 at %, it is not possible toattain the level of the heat resisting property intended in the presentinvention, the Ni or the like concentrated layer created at the contactinterface with the pixel electrodes becomes insufficient, and asatisfactory effect of reducing the contact resistance is not obtained.On the contrary, if the content of Ni or the like exceeds 6 at %, theelectrical resistivity of the Al alloy film itself increases, theresponse speed of the pixels slows down, the consumption power increasesand the quality as a display deteriorates to an impractical extent.Noting these advantages and disadvantages, it is desirable that thecontent of Ni or the like is preferably from 0.1 at % or over, morepreferably from 0.2 at % to 6 at %, and even more preferably 5 at % orless.

According to the present invention, forming the Ni or the likeconcentrated layer in the surface of the Al alloy film is effective forreduction of the contact resistance (direct contact resistance) at thecontact interface with the pixel electrodes, and the thickness of thisconcentrated layer is preferably from 0.5 nm or thicker, more preferablyfrom 1.0 nm to 10 nm, and further preferably 5 nm or thinner. Theaverage Ni concentration of this concentrated layer is preferably doubleor more of the average concentration in the entire Al alloy film, andmore preferably, 2.5 times or more.

In an Al alloy film containing Ni or the like, Ni or the like beyond thesolubility limit of Ni or the like inside the Al alloy film precipitatesat the grain boundaries of Al alloy due to thermal processing or thelike, a part of precipitating Ni or the like is diffused andconcentrated in the surface of the Al alloy film, and an Ni or the likeconcentrated layer is formed. Further, according to the presentinvention, a halide of Ni or the like, due to its low vapor pressure,does not volatilize easily during etching of a contact hole for instanceand stays in the surface of the Al alloy film, so that the concentrationof Ni or the like in the surface of the Al alloy film becomes higherthan the concentration of Ni or the like of the Al alloy bulk material.It is therefore possible to control the concentration of Ni or the likeof the surface layer, the thickness of the concentrated layer and thelike by means of proper control of conditions for the etching. Whiledepending upon the elements belonging to the groups X and Z, the elementmay get partially concentrated toward the surface layer side at thisstage, the technical scope of the present invention covers that as well.

When a display device including the TFT array substrate formed in thismanner is used as a liquid crystal display apparatus for instance, it isnot only possible to minimize the electrical resistance between thepixel electrodes and the interconnection portions for connection butalso prevent defects such as hillocks owing to the effect of theimproved heat resisting property because of the existence of theelements included in the groups X and Z. Further, since the elementsincluded in the groups X and Z form intermetallic compounds togetherwith the Al matrix material, Ni or the like and precipitate in thevicinity of the grain boundaries, recrystallization of Al which is thematrix material is facilitated and the electrical resistance of thematrix material decreases, and hence, it is possible to suppress anadverse influence over the quality of a displayed image as much aspossible.

A liquid crystal display apparatus was fabricated as an experimentaccording to the embodiment above of the present invention, and it wasconfirmed that both the production yield and the display quality wouldbe equally good as or better than those which would be obtained by acombination of an ITO film and barrier metal (of Mo, etc.). With thisliquid crystal display apparatus, it is therefore possible to achieveequivalent capabilities to those of a conventional liquid crystaldisplay apparatus, without disposing barrier metal. Hence, omission ofbarrier metal simplifies the manufacturing processing and contributes toa reduction of a manufacturing cost. Further, it is possible to realizea sufficiently low electrical resistivity at a relatively low heatingtemperature such as 250 degrees Celsius, it is possible to furtherenlarge the range of choices of the types of the materials of thedisplay device, the processing conditions, etc.

FIG. 12 is a schematic explanatory view of an enlarged cross sectionalsurface of the structure of a thin film transistor according to otherembodiment which is applicable to the array substrate of the presentinvention, and in the illustrated example, a thin film transistor havingthe top gate structure is used.

As shown in FIG. 13, a scanning line of an Al alloy film is formed on atransparent substrate 1 a, and a part of the scanning line functions asa gate electrode 26 which controls turning on and off of the thin filmtransistor. A signal line of Al alloy is formed such that the signalline intersects the scanning line via an inter-layer insulation film(SiOx), and a part of the signal line functions as a source electrode 28of the thin film transistor.

In a pixel region on the inter-layer insulation film (SiOx), there is apixel electrode 5 of an ITO film which is obtained by mixing SnO withIn₂O₃ for instance, while a drain electrode 29 of Al alloy of the thinfilm transistor functions as a connection electrode portion which iselectrically connected with the pixel electrode 5. That is, the drainelectrode 29 of Al alloy of the thin film transistor directly contactsand is electrically connected with the pixel electrode 5.

Hence, as a gate voltage is fed to the gate electrode 26 via thescanning line on the TFT array substrate as in the example shown in FIG.2 described earlier, the thin film transistor turns on and a drivevoltage fed in advance to the signal line reaches the pixel electrode 5from the source electrode 28 via the drain electrode 29, and as thedrive voltage of a predetermined level is supplied to the pixelelectrode 5, a potential difference is created from an opposed electrode10 as described in relation to FIG. 1, liquid crystal moleculescontained in a liquid crystal layer 3 are aligned and light ismodulated.

A method of producing the TFT array substrate shown in FIG. 12 will nowbe described. The thin film transistor formed in the array substrateaccording to this embodiment has the top gate structure which uses apolysilicon (poly-Si) film as a semiconductor layer. FIGS. 13 through 19are drawings which schematically show steps of producing the arraysubstrate according to the second embodiment.

First, using a plasma CVD apparatus or the like for instance, a siliconnitride (SiNx) film whose film thickness is about 50 nm and a siliconoxide (SiOx) film whose film thickness is about 100 nm are deposited ata substrate temperature of about 300 degrees Celsius for example, andfurther, an amorphous silicon hydride (a-Si:H) film whose film thicknessis about 50 nm for example is then deposited, which is followed bythermal processing and laser annealing for the purpose of turning thisamorphous silicon hydride (a-Si:H) film into polysilicon. The thermalprocessing may be atmospheric thermal processing at about 470 degreesCelsius for about one hour, and after dehydrogenation, using an eximerlaser annealing apparatus for instance, laser is irradiated upon theamorphous silicon hydride (a-Si:H) film with the energy of about 230mJ/cm² for example, whereby a polysilicon (poly-Si) film having thethickness of about 0.3 μm for instance is obtained (FIG. 13).

Following this, as shown in FIG. 14, the polysilicon (poly-Si) film ispatterned through plasma etching, etc. As shown in FIG. 15, a siliconoxide (SiOx) film is deposited into the film thickness of about 100 nmfor example, thereby obtaining a gate insulating film 27. After filmdeposition of an Al alloy film which will become the gate electrode 26integrated with the scanning line on thus obtained gate insulating film27 into the film thickness of about 200 nm for instance by sputtering orthe like, the Al alloy film is patterned by plasma etching or the like,and the gate electrode 26 integrated with the scanning line is obtained.

As shown in FIG. 16, a mask is then formed with a photoresist 31 anddoped with phosphorus at about 50 keV to 1×10¹⁵/cm² using an ionimplantation apparatus or the like for example, thereby forming an n⁺polysilicon (n⁺poly-Si) film locally within the polysilicon (poly-Si)film, and the photoresist 31 is thereafter stripped, followed by thermalprocessing at about 500 degrees Celsius for instance which causesdiffusion.

After this, as shown in FIG. 17, a silicon oxide (SiOx) film isdeposited into the film thickness of about 500 nm for example at asubstrate temperature of about 250 degrees Celsius using a plasma CVDapparatus for example, thereafter forming an inter-layer insulationfilm, a photoresist is similarly patterned, thereby dry etching theinter-layer insulation (SiOx) film and the silicon oxide film of thegate insulating film 27, contact holes are formed, and after filmdeposition of an Al alloy film by sputtering into the film thickness ofabout 450 nm for example, the Al alloy film is patterned and the sourceelectrode 28 and the drain electrode 29 integrated with the signal lineare formed. As a result, the source electrode 28 and the drain electrode29 are brought into contact with the n⁺ polysilicon (n⁺poly-Si) filmeach via a contact hole.

A silicon nitride (SiNx) film is then deposited, as an inter-layerinsulation film, into the film thickness of about 500 nm for example ata substrate temperature of about 250 degrees Celsius using a plasma CVDapparatus for example as shown in FIG. 18. After forming the photoresistlayer 31 on this, the silicon nitride (SiNx) film is patterned, and bydry etching for instance, a contact hole 32 is formed in this siliconnitride (SiNx) film.

This is followed by stripping of the photoresist using an amine-basedstripper solution or the like in a similar fashion to that describedabove after ashing by means of oxygen plasma for example as shown inFIG. 19, an ITO film is deposited as described earlier and patternedthrough wet etching, thereby forming the pixel electrode 5. While thedrain electrode 29 is brought into direct contact with the pixelelectrode 5 during this processing, the Ni or the like concentratedlayer is formed and the contact resistance decreases at the interfacebetween the Al alloy film forming the drain electrode 29 and the pixelelectrode 5, and as for the Al alloy film itself, deposition of Ni orthe elements belonging to the groups X and Z as intermetallic compoundspromotes recrystallization of Al and the electrical resistance of thisfilm itself greatly decreases.

For stabilization of transistor characteristics, annealing is thereafterperformed at about 250 degrees Celsius for about one hour, whichcompletes the polysilicon TFT array substrate.

Using the TFT array substrate according to the second embodimentdescribed above and a liquid crystal display apparatus including the TFTarray substrate, similar effects to those according to the first exampledescribed earlier are obtained. Further, as in the first example, thesecond example as well permits use of the Al alloy according to thepresent invention as a reflection electrode of a reflection-type liquidcrystal display.

The material of the pixel electrode 5 described above is preferablyindium tin oxide or indium zinc oxide, and it is desirable that theelectrical resistivity of the Al alloy film is adjusted to 7 μΩ·cm orless or more preferably 5 μΩ·cm or less by depositing some or all of thealloy components dissolved in the non-equilibrium state as intermetalliccompounds or forming the concentrated layer.

While a method of forming the Al alloy film above may be vapordeposition, sputtering or the like, sputtering is particularlypreferable.

Hence, the present invention covers a sputtering target made of Al alloywhich contains, as the materials for forming an Al alloy film having theabove composition, substantially the same composition as the compositiondescribed above, i.e., contains 0.1 to 6 at % of at least one elementselected from the group consisting of Ni, Ag, Zn, Cu and Ge as an alloycomponent and 0.1 to 2 at % of at least one element selected from thegroup consisting of Mg, Cr, Mn, Ru, Rh, Pd, Ir, Pt, La, Ce, Pr, Gd, Tb,Sm, Eu, Ho, Er, Tm, Yb, Lu and Dy or 0.1 through 1 at % of at least oneelement selected from the group consisting of Ti, V, Zr, Nb, Mo, Hf, Taand W.

Using the TFT array substrate thus obtained, a liquid crystal displayapparatus serving as a display device as that shown in FIG. 1 describedearlier is completed.

In short, the surface of the TFT array substrate thus completed iscoated with polyimide, dried and rubbed, to thereby form an orientationfilm.

On the other hand, as for an opposed substrate 2, chromium for instanceis patterned into a matrix on a glass substrate and a light shieldingfilm 9 is formed first. Color filters 8 of red, green and blue resinsare then formed in gaps within the light shielding film 9. A transparentconductive film of ITO or the like is disposed as a common electrode 7on the light shielding film 9 and the color filters 8, which completesan opposed electrode. The top-most layer of the opposed electrode iscoated with polyimide for instance, dried and rubbed, whereby anorientation film 11 is obtained.

The surface of the array substrate 1 and that of the opposed substrate 2bearing the orientation film 11 are then opposed against each other, andthe two substrates are bonded to each other by a seal material 16 whichmay be a resin except for an injection inlet for introduction of liquidcrystals. At this stage, by interposition of a spacer 15 between the twosubstrates or otherwise appropriately, the gap between the twosubstrates is maintained approximately constant.

The empty cell obtained in this manner is placed in vacuum, and with theinjection inlet immersed in liquid crystals, the pressure is returnedback to the atmospheric pressure gradually, whereby the liquid crystalmaterial containing the liquid crystals is injected into the empty cell,a liquid crystal layer is formed and the injection inlet is closed. Atlast, polarizer plates 10 are bonded to the both outer surfaces of thecell, which completes the liquid crystal panel.

Further, as shown in FIG. 1, a driver circuit for driving the liquidcrystal display apparatus is electrically connected with the liquidcrystal panel and arranged in a side portion or a back surface portionof the liquid crystal panel. With a frame including an opening servingas a display surface of the liquid crystal panel, a back light 22 actingas a surface light source, a light guide plate 20 and a holding frame23, the liquid crystal panel is held and the liquid crystal displayapparatus is completed.

EXAMPLES

While the present invention will now be described in greater detailswith reference to examples, the present invention is not restricted bythese examples but may be implemented with appropriate modification tothe extent meeting the intentions mentioned earlier and described below.Those modifications all fall within the technical scope of theinvention.

Example 1

With respect to the Al alloy films, which are shown in Tables 1, 3, 5,7, 9 and 11, having various alloy compositions, the electricalresistances and the direct contact resistances with the Al alloy filmsbrought in direct contact with pixel electrodes are measured and theheat resisting properties (hillock density) upon heating of the Al alloyfilms at 250 degrees Celsius for 30 minutes are investigated.

The experiment to obtain the measurements is as described below.

1) Structure of the pixel electrodes: Indium tin oxide (ITO) obtained byadding 10 mass % tin oxide to indium oxide

2) Thin film forming conditions: Gas atmosphere=Ar, Pressure=3 mTorr,Film thickness=200 nm

3) Heating condition: 250 degrees Celsius×30 minutes

4) Content of each element contained in Al alloy: Content of eachelement contained in Al alloys which are investigated in this Examplewas measured by using ICP (Inductive Coupled Plasma) emissionspectrometry method.

5) Method of measuring the electrical resistivity of the Al alloy thinfilm: The electrical resistivity of the Al alloy thin film was measuredby 4-terminal measurement using Kelvin patterns, and those exhibited theelectrical resistivity of 7 μΩ·cm or lower were determined favorable (∘)but those exhibited the electrical resistivity exceeding 7 μΩ·cm weredetermined defective (x).

6) Method of measuring the direct contact resistivity: Kelvin patternsas those shown in FIG. 20 (having the contact hole size of 10 μm×10 μm)were fabricated, and 4-terminal measurement (a method according to whicha current was supplied to ITO-Al alloy and a voltage drop between ITO-Alalloy was measured using a different terminal) was performed. In short,a current I was fed between I₁ and I₂ shown in FIG. 20, a voltage Vbetween V₁ and V₂ was monitored, the direct contact resistance R in acontact portion C was accordingly calculated as [R=(V₂−V₁)/I₂], andthose exhibited the contact resistance of 1 kΩ or lower were determinedfavorable (∘) but those exhibited the contact resistance exceeding 1 kΩwere determined defective (x).

7) Method of measuring the heat resisting properties: Under theconditions described in 3), Al alloy thin films alone were formed onglass substrates. Then line-and-space patterns whose widths were 10 μmwere formed, vacuum heat treatment was performed at 250 degrees Celsiusfor 30 minutes, the surfaces of interconnections were observed with SEM,and the number of hillocks having the diameters of 0.1 μm or larger wascounted. Those exhibited the hillock density of 1×10⁻⁹/m² or lower weredetermined favorable (∘) but those exhibited the hillock densityexceeding 1×10⁻⁹/m² were determined defective (x).

8) Method of measuring the thickness of the concentrated layercontaining α and the content of α in the concentrated layer: Withrespect to a part of the samples shown in Tables 1, 3, 5, 7, 9 and 11,the film thicknesses after thermal processing of the α concentratedlayers (Ni-concentrated layer in Table 1, Ag-concentrated layer in Table2, Zn-concentrated layer in Table 3, Cu-concentrated layer in Table 4,and Ge-concentrated layer in Table 5) were identified through crosssectional TEM observation using “FE-TEM HF-2000” manufactured byHitachi, Ltd. Furthermore, the contents of α in the α-concentratedlayers were determined by component analysis from cross sectional TEMsamples using EDX (Sigma manufactured by KEVEX).

The results are added to Tables 1 through 10.

TABLE 1 Heat Resisting Electric Resistance (after Third Element (X)Property heating at 250° C. for 30 min) The Amount (hillock density)Direct Contact No. Base Alloy Type Added (at %) (250° C.) Film MaterialResistance 1 Al—2at % Ni — — X ◯ ◯ 2 Al—2at % Ni Nd 0.6 ◯ X ◯ 3 Al—2at %Ni—X Pt 0.01 X ◯ ◯ 4 Mg 1 ◯ ◯ ◯ 5 Cr 1 ◯ ◯ ◯ 6 Mn 1 ◯ ◯ ◯ 7 Ru 1 ◯ ◯ ◯ 8Rh 1 ◯ ◯ ◯ 9 Pd 1 ◯ ◯ ◯ 10 Ir 1 ◯ ◯ ◯ 11 Pt 1 ◯ ◯ ◯ 12 La 1 ◯ ◯ ◯ 13 Gd1 ◯ ◯ ◯ 14 Tb 1 ◯ ◯ ◯ 15 Dy 1 ◯ ◯ ◯ 16 Ce 1 ◯ ◯ ◯ 17 Sm 1 ◯ ◯ ◯ 18 Eu 1◯ ◯ ◯ 19 Er 1 ◯ ◯ ◯ 20 Pt 2.5 ◯ X ◯ 21 Ir 2.5 ◯ X ◯ 22 Al—2at % Ni—Z W0.01 X ◯ ◯ 23 Ti 0.5 ◯ ◯ ◯ 24 V 0.5 ◯ ◯ ◯ 25 Zr 0.5 ◯ ◯ ◯ 26 Nb 0.5 ◯ ◯◯ 27 Mo 0.5 ◯ ◯ ◯ 28 Hf 0.5 ◯ ◯ ◯ 29 Ta 0.5 ◯ ◯ ◯ 30 W 0.5 ◯ ◯ ◯ 31 Nb2.5 ◯ X ◯ 32 Ta 1.5 ◯ X ◯ 33 Al—2at % Ni Sn 1 X ◯ ◯ 34 Al—0.05at % Ni—XPt 1 ◯ ◯ X 35 Al—1 at % Ni—X ◯ ◯ ◯ 36 Al—3at % Ni—X ◯ ◯ ◯ 37 Al—6at %Ni—X ◯ ◯ ◯ 38 Al—8at % Ni—X ◯ X ◯ 39 Al—0.05at % Ni—Z Ta 0.5 ◯ ◯ X 40Al—1 at % Ni—Z ◯ ◯ ◯ 41 Al—3at % Ni—Z ◯ ◯ ◯ 42 Al—6at % Ni—Z ◯ ◯ ◯ 43Al—8at % Ni—Z ◯ X ◯

It is noted that, in Table 1, the film thickness of the Ni-concentratedlayer and the content of Ni in the Ni-concentrated layer were measuredafter thermal processing for each sample which satisfied the conditionsof the present invention. In the result, the film thickness of the eachNi-concentrated layer was within the range of about 0.5 to 2 nm, and thecontent of Ni in the each Ni-concentrated layer was generally within therange of twice to nine times as much as the average content of Ni ineach thin film of Al alloy (not shown in Table 1).

In Table 1, the results of experiments are shown, in which amounts ofthe third elements selected from the elements belonging to the group Xor Z were changed. It was confirmed that similar results of theexperiments could be obtained when other elements belonging to the groupX or Z and not listed in Table 1 were used as the third elements.

TABLE 2 Direct Contact Resistance (10 μm × 10 μm Contact Hall) No.Composition Contact Resistivity (Ω) Value 1 Al—6 at % Ni 10 ⊚ 2 Al—6 at% Ni—0.5 at % La 22 ⊚ 3 Al—2 at % Ni 100 ⊚ 4 Al—2 at % Ni—0.5 at % La 73⊚ 5 Al—2 at % Ni—1.8 at % La 73 ⊚ 6 Al—2 at % Ni—0.8 at % Gd 29 ⊚ 7 Al—2at % Ni—0.3 at % Mn 153 ⊚ 8 Al—0.1 at % Ni 317 ⊚ 9 Al—0.1 at % Ni—0.5 at% La 332 ◯ 10 Al 5 × 10⁵ X 11 Mo 10 ⊚

TABLE 3 Heat Resisting Electric Resistance (after Third Element (X)Property heating at 250° C. for 30 min) The Amount (hillock density)Direct Contact No. Base Alloy Type Added (at %) (250° C.) Film MaterialResistance 1 Al—2at % Ag — — X ◯ ◯ 2 Al—2at % Ag Nd 0.6 ◯ X ◯ 3 Al—2at %Ag—X Pt 0.01 X ◯ ◯ 4 Mg 1 ◯ ◯ ◯ 5 Cr 1 ◯ ◯ ◯ 6 Mn 1 ◯ ◯ ◯ 7 Ru 1 ◯ ◯ ◯ 8Rh 1 ◯ ◯ ◯ 9 Pd 1 ◯ ◯ ◯ 10 Ir 1 ◯ ◯ ◯ 11 Pt 1 ◯ ◯ ◯ 12 Gd 1 ◯ ◯ ◯ 13 Tb1 ◯ ◯ ◯ 14 Dy 1 ◯ ◯ ◯ 15 Ce 1 ◯ ◯ ◯ 16 Sm 1 ◯ ◯ ◯ 17 Eu 1 ◯ ◯ ◯ 18 Er 1◯ ◯ ◯ 19 Pt 2 ◯ X ◯ 20 Ir 2.5 ◯ X ◯ 21 Al—2at % Ag—Z W 0.01 X ◯ ◯ 22 Ti0.5 ◯ ◯ ◯ 23 V 0.5 ◯ ◯ ◯ 24 Zr 0.5 ◯ ◯ ◯ 25 Nb 0.5 ◯ ◯ ◯ 26 Mo 0.5 ◯ ◯ ◯27 Hf 0.5 ◯ ◯ ◯ 28 W 0.5 ◯ ◯ ◯ 29 Nb 2.5 ◯ X ◯ 30 Ta 1.5 ◯ X ◯ 31 Al—2at% Ag Sn 1 X ◯ ◯ 32 Al—0.05at % Ag—X La 1 ◯ ◯ X 33 Al—0.1 at % Ag—X ◯ ◯ ◯34 Al—1 at % Ag—X ◯ ◯ ◯ 35 Al—2at % Ag—X ◯ ◯ ◯ 36 Al—6at % Ag—X ◯ X ◯ 37Al—0.05at % Ag—Z Ta 0.5 ◯ ◯ X 38 Al—0.1 at % Ag—Z ◯ ◯ ◯ 39 Al—1 at %Ag—Z ◯ ◯ ◯ 40 Al—2at % Ag—Z ◯ ◯ ◯ 41 Al—6at % Ag—Z ◯ X ◯

It is noted that, in Table 3, the film thickness of the Ag-concentratedlayer and the content of Ag in the Ag-concentrated layer were measuredafter thermal processing for each sample which satisfied the conditionsof the present invention. In the result, the film thickness of the eachAg-concentrated layer was within the range of about 0.5 to 2 nm, and thecontent of Ag in the each Ag-concentrated layer was generally within therange of twice to nine times as much as the average content of Ag ineach thin film of Al alloy (not shown in Table 3).

In Table 3, the results of experiments are shown, in which amounts ofthe third elements selected from the elements belonging to the group Xor Z were changed. It was confirmed that similar results of theexperiments could be obtained when other elements belonging to the groupX or Z and not listed in Table 3 were used as the third elements.

TABLE 4 Direct Contact Resistance (10 μm × 10 μm Contact Hall) No.Composition Contact Resistivity (Ω) Value 1 Al—6 at % Ag 8 ⊚ 2 Al—6 at %Ag—0.5 at % La 12 ⊚ 3 Al—2 at % Ag 40 ⊚ 4 Al—2 at % Ag—0.5 at % La 39 ⊚5 Al—2 at % Ag—1.8 at % Mg 35 ⊚ 6 Al—2 at % Ag—0.8 at % Gd 35 ⊚ 7 Al—0.1at % Ag 220 ◯ 8 Al—0.1 at % Ag—0.5 at % La 255 ◯

TABLE 5 Heat Resisting Electric Resistance (after Third Element (X)Property heating at 250° C. for 30 min) The Amount (hillock density)Direct Contact No. Base Alloy Type Added (at %) (250° C.) Film MaterialResistance 1 Al—2at % Zn — — X ◯ ◯ 2 Al—2at % Zn Nd 0.6 ◯ X ◯ 3 Al—2at %Zn—X Pt 0.01 X ◯ ◯ 4 Mg 1 ◯ ◯ ◯ 5 Cr 1 ◯ ◯ ◯ 6 Mn 1 ◯ ◯ ◯ 7 Ru 1 ◯ ◯ ◯ 8Rh 1 ◯ ◯ ◯ 9 Pd 1 ◯ ◯ ◯ 10 Ir 1 ◯ ◯ ◯ 11 Pt 1 ◯ ◯ ◯ 12 Gd 1 ◯ ◯ ◯ 13 Tb1 ◯ ◯ ◯ 14 Dy 1 ◯ ◯ ◯ 15 Ce 1 ◯ ◯ ◯ 16 Sm 1 ◯ ◯ ◯ 17 Eu 1 ◯ ◯ ◯ 18 Er 1◯ ◯ ◯ 19 Pt 2 ◯ X ◯ 20 Ir 2.5 ◯ X ◯ 21 Al—2at % Zn—Z W 0.01 X ◯ ◯ 22 Ti0.5 ◯ ◯ ◯ 23 V 0.5 ◯ ◯ ◯ 24 Zr 0.5 ◯ ◯ ◯ 25 Nb 0.5 ◯ ◯ ◯ 26 Mo 0.5 ◯ ◯ ◯27 Hf 0.5 ◯ ◯ ◯ 28 W 0.5 ◯ ◯ ◯ 29 Nb 2.5 ◯ X ◯ 30 Ta 1.5 ◯ X ◯ 31 Al—2at% Zn Sn 1 X ◯ ◯ 32 Al—0.05at % Zn—X La 1 ◯ ◯ X 33 Al—0.1 at % Zn—X ◯ ◯ ◯34 Al—1 at % Zn—X ◯ ◯ ◯ 35 Al—2at % Zn—X ◯ ◯ ◯ 36 Al—6at % Zn—X ◯ X ◯ 37Al—0.05at % Zn—Z 0.5 ◯ ◯ X 38 Al—0.1 at % Zn—Z ◯ ◯ ◯ 39 Al—1 at % Zn—Z ◯◯ ◯ 40 Al—2at % Zn—Z ◯ ◯ ◯ 41 Al—6at % Zn—Z ◯ X ◯

It is noted that, in Table 5, the film thickness of the Zn-concentratedlayer and the content of Zn in the Zn-concentrated layer were measuredafter thermal processing for each sample which satisfied the conditionsof the present invention. In the result, the film thickness of the eachZn-concentrated layer was within the range of about 0.5 to 2 nm, and thecontent of Zn in the each Zn-concentrated layer was generally within therange of twice to nine times as much as the average content of Zn ineach thin film of Al alloy (not shown in Table 5).

In Table 5, the results of experiments are shown, in which amounts ofthe third elements selected from the elements belonging to the group Xor Z were changed. It was confirmed that similar results of theexperiments could be obtained when other elements belonging to the groupX or Z and not listed in Table 5 were used as the third elements.

TABLE 6 Direct Contact Resistance (10 μm × 10 μm Contact Hall) No.Composition Contact Resistivity (Ω) Value 1 Al—6 at % Zn 33 ⊚ 2 Al—6 at% Zn—0.5 at % La 50 ⊚ 3 Al—2 at % Zn 152 ⊚ 4 Al—2 at % Zn—0.5 at % La121 ⊚ 5 Al—2 at % Zn—1.8 at % Mg 108 ⊚ 6 Al—2 at % Zn—0.8 at % Gd 97 ⊚ 7Al—0.1 at % Zn 405 ◯ 8 Al—0.1 at % Zn—0.5 at % La 325 ◯

TABLE 7 Heat Resisting Electric Resistance (after Third Element (X)Property heating at 250° C. for 30 min) The Amount (hillock density)Direct Contact No. Base Alloy Type Added (at %) (250° C.) Film MaterialResistance 1 Al—2at % Cu — — X ◯ ◯ 2 Al—2at % Cu Nd 0.6 ◯ X ◯ 3 Al—2at %Cu—X Pt 0.01 X ◯ ◯ 4 Mg 1 ◯ ◯ ◯ 5 Cr 1 ◯ ◯ ◯ 6 Mn 1 ◯ ◯ ◯ 7 Ru 1 ◯ ◯ ◯ 8Rh 1 ◯ ◯ ◯ 9 Pd 1 ◯ ◯ ◯ 10 Ir 1 ◯ ◯ ◯ 11 Pt 1 ◯ ◯ ◯ 12 Gd 1 ◯ ◯ ◯ 13 Tb1 ◯ ◯ ◯ 14 Dy 1 ◯ ◯ ◯ 15 Ce 1 ◯ ◯ ◯ 16 Sm 1 ◯ ◯ ◯ 17 Eu 1 ◯ ◯ ◯ 18 Er 1◯ ◯ ◯ 19 Pt 2 ◯ X ◯ 20 Ir 2.5 ◯ X ◯ 21 Al—2at % Cu—Z W 0.01 X ◯ ◯ 22 Ti0.5 ◯ ◯ ◯ 23 V 0.5 ◯ ◯ ◯ 24 Zr 0.5 ◯ ◯ ◯ 25 Nb 0.5 ◯ ◯ ◯ 26 Mo 0.5 ◯ ◯ ◯27 Hf 0.5 ◯ ◯ ◯ 28 W 0.5 ◯ ◯ ◯ 29 Nb 2.5 ◯ X ◯ 30 Ta 1.5 ◯ X ◯ 31 Al—2at% Cu Sn 1 X ◯ ◯ 32 Al—0.05at % Cu—X La 1 ◯ ◯ X 33 Al—0.1at % Cu—X ◯ ◯ ◯34 Al—1at % Cu—X ◯ ◯ ◯ 35 Al—2at % Cu—X ◯ ◯ ◯ 36 Al—6at % Cu—X ◯ X ◯ 37Al—0.05at % Cu—Z Ta 0.5 ◯ ◯ X 38 Al—0.1at % Cu—Z ◯ ◯ ◯ 39 Al—1at % Cu—Z◯ ◯ ◯ 40 Al—2at % Cu—Z ◯ ◯ ◯ 41 Al—6at % Cu—Z ◯ X ◯

It is noted that, in Table 7, the film thickness of the Cu-concentratedlayer and the content of Cu in the Cu-concentrated layer were measuredafter thermal processing for each sample which satisfied the conditionsof the present invention. In the result, the film thickness of the eachCu-concentrated layer was within the range of about 0.5 to 2 nm, and thecontent of Cu in the each Cu-concentrated layer was generally within therange of twice to nine times as much as the average content of Cu ineach thin film of Al alloy (not shown in Table 7).

In Table 7, the results of experiments are shown, in which amounts ofthe third elements selected from the elements belonging to the group Xor Z were changed. It was confirmed that similar results of theexperiments could be obtained when other elements belonging to the groupX or Z and not listed in Table 7 were used as the third elements.

TABLE 8 Direct Contact Resistance (10 μm × 10 μm Contact Hall) No.Composition Contact Resistivity (Ω) Value 1 Al—6 at % Cu 335 ⊚ 2 Al—6 at% Cu—0.5 at % La 285 ⊚ 3 Al—2 at % Cu 190 ◯ 4 Al—2 at % Cu—0.5 at % La192 ◯ 5 Al—2 at % Cu—1.8 at % Mg 256 ◯ 6 Al—2 at % Cu—0.8 at % Gd 222 ◯7 Al—0.1 at % Cu 215 ◯ 8 Al—0.1 at % Cu—0.5 at % La 320 ◯

TABLE 9 Electric Resistance Heat Resisting (after heating at ThirdElement (X) Property 250° C. for 30 min) The Amount (hillock density)Film Direct Contact No. Base Alloy Type Added (at %) (250° C.) MaterialResistance 1 Al—2at % Ge — — X ◯ ◯ 2 Al—2at % Ge Nd 0.6 ◯ X ◯ 3 Al—2at %Ge—X Pt 0.01 X ◯ ◯ 4 Mg 1 ◯ ◯ ◯ 5 Cr 1 ◯ ◯ ◯ 6 Mn 1 ◯ ◯ ◯ 7 Ru 1 ◯ ◯ ◯ 8Rh 1 ◯ ◯ ◯ 9 Pd 1 ◯ ◯ ◯ 10 Ir 1 ◯ ◯ ◯ 11 Pt 1 ◯ ◯ ◯ 12 Gd 1 ◯ ◯ ◯ 13 Tb1 ◯ ◯ ◯ 14 Dy 1 ◯ ◯ ◯ 15 Ce 1 ◯ ◯ ◯ 16 Sm 1 ◯ ◯ ◯ 17 Eu 1 ◯ ◯ ◯ 18 Er 1◯ ◯ ◯ 19 Pt 2 ◯ X ◯ 20 Ir 2.5 ◯ X ◯ 21 Al—2at % Ge—Z W 0.01 X ◯ ◯ 22 Ti0.5 ◯ ◯ ◯ 23 V 0.5 ◯ ◯ ◯ 24 Zr 0.5 ◯ ◯ ◯ 25 Nb 0.5 ◯ ◯ ◯ 26 Mo 0.5 ◯ ◯ ◯27 Hf 0.5 ◯ ◯ ◯ 28 W 0.5 ◯ ◯ ◯ 29 Nb 2.5 ◯ X ◯ 30 Ta 1.5 ◯ X ◯ 31 Al—2at% Ge Sn 1 X ◯ ◯ 32 Al—0.05at % Ge—X La 1 ◯ ◯ X 33 Al—0.1at % Ge—X ◯ ◯ ◯34 Al—1at % Ge—X ◯ ◯ ◯ 35 Al—2at % Ge—X ◯ ◯ ◯ 36 Al—6at % Ge—X ◯ X ◯ 37Al—0.05at % Ge—Z Ta 0.5 ◯ ◯ X 38 Al—0.1at % Ge—Z ◯ ◯ ◯ 39 Al—1at % Ge—Z◯ ◯ ◯ 40 Al—2at % Ge—Z ◯ ◯ ◯ 41 Al—6at % Ge—Z ◯ X ◯

It is noted that, in Table 9, the film thickness of the Ge-concentratedlayer and the content of Ge in the Ge-concentrated layer were measuredafter thermal processing for each sample which satisfied the conditionsof the present invention. In the result, the film thickness of the eachGe-concentrated layer was within the range of about 0.5 to 2 nm, and thecontent of Ge in the each Ge-concentrated layer was generally within therange of twice to nine times as much as the average content of Ge ineach thin film of Al alloy (not shown in Table 9).

In Table 9, the results of experiments are shown, in which amounts ofthe third elements selected from the elements belonging to the group Xor Z were changed. It was confirmed that similar results of theexperiments could be obtained when other elements belonging to the groupX or Z and not listed in Table 9 were used as the third elements.

TABLE 10 Direct Contact Resistance (10 μm × 10 μm Contact Hall) No.Composition Contact Resistivity (Ω) Value 1 Al—6 at % Ge 23 ⊚ 2 Al—6 at% Ge—0.5 at % La 44 ⊚ 3 Al—2 at % Ge 150 ⊚ 4 Al—2 at % Ge—0.5 at % La123 ⊚ 5 Al—0.1 at % Ge 335 ◯ 6 Al—0.1 at % Ge—0.5 at % La 285 ◯

According to the experimental results shown in Tables 1 through 10, itis possible to suppress the electrical resistance of an Al alloy filmitself and the contact resistance with pixel electrodes at low levelswhile securing a sufficient heat resisting property at a relatively lowheating temperature such as 250 degrees Celsius. And therefore, it ispossible to use a material which has heretofore been impossible to usedue to its insufficient heat resisting property as the material of thedisplay device and thus provide richer offerings of material choices.

Example 2

In this example, as described hereinafter, resistance against analkaline solution using TMAH developing solution and presence or absenceof a pitting corrosion were investigated about each sample of an Alalloy thin films having various alloy compositions listed in Tables 11through 15.

In particular, Al alloy films were formed on glass substrates under theconditions described in 3) of above-described Example 1. Each of the Alalloy films obtained by the above step was directly immersed at 25degrees Celsius in ordinary developing solutions (solutions containing2.38 mass % TMAH), the time until the films got completely dissolved wasmeasured, the etching rates per unit time (one minute) were calculatedfrom thus measured time and the amounts of adhering films, and theresistance against an alkaline solution was evaluated in accordance withthe following criteria. ∘: the etching rate slower than 40 nm/min, Δ:the etching rate of 40 nm/min or faster but slower than 70 nm/min, x:the etching rate of 70 nm/min or faster.

The presence or absence of pitting corrosions was investigated by asurface observation under the optical microscope (magnification: 400×),and was confirmed by an observation with SEM (magnification: 3000×). Inthe result, those having no foreign particles (pitting corrosions) weredetermined as “absence” but those having foreign particles (pittingcorrosions) were determined as “presence”.

For comparison, the etching rate, the resistance against alkalinedeveloping solution, and the presence or absence of pitting corrosionswere investigated for a pure Aluminum thin film instead of the Al alloythin film.

Tables 11 through 15 shows the results.

TABLE 11 Etching Rate in Resistance against Developing Solution AlkalineDeveloping Pitting No. Composition (nm/min) Solution Corrosion 1 Al—6 at% Ni 80 X absence 2 Al—2 at % Ni 120 X absence 3 Al—0.5 at % Ni 105 Xabsence 4 Al—2 at % Ni—0.6 at % Nd 61 Δ absence 5 Al—2 at % Ni—0.2 at %Nd 90 X absence 6 Al—2 at % Ni—0.6 at % Mn 40 ◯ absence 7 Al—2 at %Ni—0.5 at % La 29 ◯ absence 8 Al—2 at % Ni—0.3 at % V 24 ◯ absence 9Al—2 at % Ni—1.8 at % Mg 10 ◯ absence 10 Al—2 at % Ni—0.08 at % Mg 110 Xabsence 11 Al—2 at % Ni—0.8 at % Gd 7 ◯ absence 12 Al—2 at % Ni—1 at %Dy 38 ◯ absence 13 Al—2 at % Ni—1 at % Tb 40 ◯ absence 14 Al—2 at %Ni—0.5 at % Pt 120 X absence 15 Al—0.1 at % Ni—0.6 at % Mn 26 ◯ absence16 Al—0.1 at % Ni—0.5 at % La 18 ◯ absence 17 Al—0.1 at % Ni—0.3 at % V16 ◯ absence 18 Al—0.1 at % Ni—1.8 at % Mg 7 ◯ absence 19 Al—0.1 at %Ni—0.8 at % Gd 5 ◯ absence 20 Al—6 at % Ni—0.6 at % Mn 32 ◯ absence 21Al—6 at % Ni—0.5 at % La 24 ◯ absence 22 Al—6 at % Ni—0.3 at % V 20 ◯absence 23 Al—6 at % Ni—1.8 at % Mg 8 ◯ absence 24 Al—6 at % Ni—0.8 at %Gd 6 ◯ absence 25 Al—2 at % Ni—0.5 at % Ta 40 ◯ absence 26 Al—2 at %Ni—0.5 at % Sm 39 ◯ absence 27 Al—2 at % Ni—0.5 at % Eu 40 ◯ absence 28Al—2 at % Ni—0.5 at % Er 40 ◯ absence 29 Al 20 ◯ absence

TABLE 12 Etching Rate in Resistance against Developing Solution AlkalineDeveloping Pitting No. Composition (nm/min) Solution Corrosion 1 Al—6 at% Ag 55 X presence 2 Al—2 at % Ag 42 X presence 3 Al—0.5 at % Ag 40 Xpresence 4 Al—2 at % Ag—0.6 at % Nd 48 Δ absence 5 Al—2 at % Ag—0.2 at %Nd 50 X presence 6 Al—2 at % Ag—0.6 at % Mn 39 ◯ absence 7 Al—2 at %Ag—0.5 at % La 35 ◯ absence 8 Al—2 at % Ag—0.3 at % V 30 ◯ absence 9Al—2 at % Ag—1.8 at % Mg 22 ◯ absence 10 Al—2 at % Ag—0.08 at % Mg 42 Xpresence 11 Al—2 at % Ag—0.8 at % Gd 9 ◯ absence 12 Al—2 at % Ag—1 at %Dy 32 ◯ absence 13 Al—2 at % Ag—1 at % Tb 32 ◯ absence 14 Al—2 at %Ag—0.5 at % Pt 75 X presence 15 Al—0.1 at % Ag—0.6 at % Mn 12 ◯ absence16 Al—0.1 at % Ag—0.5 at % La 7 ◯ absence 17 Al—0.1 at % Ag—0.3 at % V10 ◯ absence 18 Al—0.1 at % Ag—1.8 at % Mg 10 ◯ absence 19 Al—0.1 at %Ag—0.8 at % Gd 5 ◯ absence 20 Al—6 at % Ag—0.6 at % Mn 39 ◯ absence 21Al—6 at % Ag—0.5 at % La 34 ◯ absence 22 Al—6 at % Ag—0.3 at % V 30 ◯absence 23 Al—6 at % Ag—1.8 at % Mg 22 ◯ absence 24 Al—6 at % Ag—0.8 at% Gd 14 ◯ absence 25 Al—2 at % Ag—0.5 at % Ta 35 ◯ absence 26 Al—2 at %Ag—0.5 at % Sm 40 ◯ absence 27 Al—2 at % Ag—0.5 at % Eu 35 ◯ absence 28Al—2 at % Ag—0.5 at % Er 37 ◯ absence

TABLE 13 Etching Rate in Resistance against Developing Solution AlkalineDeveloping Pitting No. Composition (nm/min) Solution Corrosion 1 Al—6 at% Zn 40 X presence 2 Al—2 at % Zn 30 X presence 3 Al—0.5 at % Zn 28 Xpresence 4 Al—2 at % Zn—0.6 at % Nd 15 Δ absence 5 Al—2 at % Zn—0.2 at %Nd 25 X presence 6 Al—2 at % Zn—0.6 at % Mn 20 ◯ absence 7 Al—2 at %Zn—0.5 at % La 15 ◯ absence 8 Al—2 at % Zn—0.3 at % V 25 ◯ absence 9Al—2 at % Zn—1.8 at % Mg 16 ◯ absence 10 Al—2 at % Zn—0.08 at % Mg 33 Xpresence 11 Al—2 at % Zn—0.8 at % Gd 8 ◯ absence 12 Al—2 at % Zn—1 at %Dy 28 ◯ absence 13 Al—2 at % Zn—1 at % Tb 25 ◯ absence 14 Al—2 at %Zn—0.5 at % Pt 65 X presence 15 Al—0.1 at % Zn—0.6 at % Mn 17 ◯ absence16 Al—0.1 at % Zn—0.5 at % La 10 ◯ absence 17 Al—0.1 at % Zn—0.3 at % V12 ◯ absence 18 Al—0.1 at % Zn—1.8 at % Mg 3 ◯ absence 19 Al—0.1 at %Zn—0.8 at % Gd 4 ◯ absence 20 Al—6 at % Zn—0.6 at % Mn 31 ◯ absence 21Al—6 at % Zn—0.5 at % La 25 ◯ absence 22 Al—6 at % Zn—0.3 at % V 28 ◯absence 23 Al—6 at % Zn—1.8 at % Mg 20 ◯ absence 24 Al—6 at % Zn—0.8 at% Gd 10 ◯ absence 25 Al—2 at % Zn—0.5 at % Ta 25 ◯ absence 26 Al—2 at %Zn—0.5 at % Sm 25 ◯ absence 27 Al—2 at % Zn—0.5 at % Eu 30 ◯ absence 28Al—2 at % Zn—0.5 at % Er 28 ◯ absence

TABLE 14 Etching Rate in Resistance against Developing Solution AlkalineDeveloping Pitting No. Composition (nm/min) Solution Corrosion 1 Al—6 at% Ge 33 X presence 2 Al—2 at % Ge 25 X presence 3 Al—0.5 at % Ge 25 Xpresence 4 Al—2 at % Ge—0.6 at % Nd 9 Δ absence 5 Al—2 at % Ge—0.2 at %Nd 21 X presence 6 Al—2 at % Ge—0.6 at % Mn 15 ◯ absence 7 Al—2 at %Ge—0.5 at % La 18 ◯ absence 8 Al—2 at % Ge—0.3 at % V 22 ◯ absence 9Al—2 at % Ge—1.8 at % Mg 11 ◯ absence 10 Al—2 at % Ge—0.08 at % Mg 28 Xpresence 11 Al—2 at % Ge—0.8 at % Gd 9 ◯ absence 12 Al—2 at % Ge—1 at %Dy 20 ◯ absence 13 Al—2 at % Ge—1 at % Tb 40 ◯ absence 14 Al—2 at %Ge—0.5 at % Pt 63 X presence 15 Al—0.1 at % Ge—0.6 at % Mn 13 ◯ absence16 Al—0.1 at % Ge—0.5 at % La 14 ◯ absence 17 Al—0.1 at % Ge—0.3 at % V18 ◯ absence 18 Al—0.1 at % Ge—1.8 at % Mg 13 ◯ absence 19 Al—0.1 at %Ge—0.8 at % Gd 5 ◯ absence 20 Al—6 at % Ge—0.6 at % Mn 32 ◯ absence 21Al—6 at % Ge—0.5 at % La 30 ◯ absence 22 Al—6 at % Ge—0.3 at % V 31 ◯absence 23 Al—6 at % Ge—1.8 at % Mg 25 ◯ absence 24 Al—6 at % Ge—0.8 at% Gd 19 ◯ absence 25 Al—2 at % Ge—0.5 at % Ta 22 ◯ absence 26 Al—2 at %Ge—0.5 at % Sm 21 ◯ absence 27 Al—2 at % Ge—0.5 at % Eu 33 ◯ absence 28Al—2 at % Ge—0.5 at % Er 32 ◯ absence

TABLE 15 Etching Rate in Resistance against Developing Solution AlkalineDeveloping Pitting No. Composition (nm/min) Solution Corrosion 1 Al—6 at% Cu 58 X presence 2 Al—2 at % Cu 48 X presence 3 Al—0.5 at % Cu 48 Xpresence 4 Al—2 at % Cu—0.6 at % Nd 43 Δ absence 5 Al—2 at % Cu—0.2 at %Nd 48 X presence 6 Al—2 at % Cu—0.6 at % Mn 40 ◯ absence 7 Al—2 at %Cu—0.5 at % La 31 ◯ absence 8 Al—2 at % Cu—0.3 at % V 22 ◯ absence 9Al—2 at % Cu—1.8 at % Mg 15 ◯ absence 10 Al—2 at % Cu—0.08 at % Mg 42 Xpresence 11 Al—2 at % Cu—0.8 at % Gd 12 ◯ absence 12 Al—2 at % Cu—1 at %Dy 33 ◯ absence 13 Al—2 at % Cu—1 at % Tb 38 ◯ absence 14 Al—2 at %Cu—0.5 at % Pt 85 X presence 15 Al—0.1 at % Cu—0.6 at % Mn 20 ◯ absence16 Al—0.1 at % Cu—0.5 at % La 12 ◯ absence 17 Al—0.1 at % Cu—0.3 at % V16 ◯ absence 18 Al—0.1 at % Cu—1.8 at % Mg 10 ◯ absence 19 Al—0.1 at %Cu—0.8 at % Gd 10 ◯ absence 20 Al—6 at % Cu—0.6 at % Mn 40 ◯ absence 21Al—6 at % Cu—0.5 at % La 30 ◯ absence 22 Al—6 at % Cu—0.3 at % V 35 ◯absence 23 Al—6 at % Cu—1.8 at % Mg 25 ◯ absence 24 Al—6 at % Cu—0.8 at% Gd 22 ◯ absence 25 Al—2 at % Cu—0.5 at % Ta 40 ◯ absence 26 Al—2 at %Cu—0.5 at % Sm 27 ◯ absence 27 Al—2 at % Cu—0.5 at % Eu 26 ◯ absence 28Al—2 at % Cu—0.5 at % Er 38 ◯ absence

1. A display device in which an Al alloy film and a conductive oxidefilm are directly connected without interposition of refractory metaland some or all of Al alloy components deposit or are concentrated atthe interface of contact between the Al alloy film and the conductiveoxide film, wherein the Al alloy film comprises 0.1 to 6 at % of atleast one element selected from the group consisting of Ni, Cu and Ge,and 0.1 to 2 at % of at least one element selected from the groupconsisting of Rh, Ir, La, Ce, Pr, Gd, Tb, Eu, Ho, Er, Tm, Yb, Lu and Dyas alloy components, and wherein the components selected from the groupconsisting of Ni, Cu and Ge concentrate at the interface of contact in alayer of thickness of from 1 to 5 nm.
 2. A display device in which an Alalloy film and a conductive oxide film are directly connected withoutinterposition of refractory metal and some or all of Al alloy componentsdeposit or are concentrated at the interface of contact between the Alalloy film and the conductive oxide film, wherein the Al alloy filmcomprises 0.1 to 6 at % of at least one element selected from the groupcontaining of Ni, Cu and Ge, and 0.1 to 1 at % of V, as alloycomponents, and wherein the components selected from the groupconsisting of Ni, Cu and Ge concentrate at the interface of contact in alayer of thickness of from 1 to 5 nm.
 3. The display device according toclaim 1, wherein the electrical resistivity of the Al alloy film is 7μΩ·cm or less after heat treatment at 250 degrees Celsius for 30minutes.
 4. The display device according to claim 2, wherein theelectrical resistivity of the Al alloy film is 7 μΩ·cm or less afterheat treatment at 250 degrees Celsius for 30 minutes.
 5. The displaydevice according to claim 1, wherein the components selected from thegroup consisting of Rh, Ir, La, Ce, Pr, Gd, Tb, Eu, Ho, Er, Tm, Yb, Luand Dy are present in an amount of 0.3 to 1.8 at %.
 6. The displaydevice according to claim 2, wherein the V is present in an amount of0.2 to 0.8 at %.
 7. The display device according to claim 1, wherein thecomponents selected from the group consisting of Ni, Cu and Ge arepresent in an amount of 0.2 to 5.0 at %.
 8. The display device accordingto claim 2, wherein the components selected from the group consisting ofNi, Cu and Ge are present in an amount of 0.2 to 5.0 at %.
 9. Thedisplay device according to claim 1, wherein the Ni group componentsconcentration in said layer is 2.5 times or more the averageconcentration in the Al alloy film.
 10. The display device according toclaim 2, wherein the Ni group components concentration in said layer is2.5 times or more the average concentration in the Al alloy film. 11.The display device according to claim 1, wherein the electricalresistivity of the Al alloy film is 5 μΩ·cm or less after heat treatmentat 250 degrees Celsius for 30 minutes.
 12. The display device accordingto claim 2, wherein the electrical resistivity of the Al alloy film is 5μΩ·cm or less after heat treatment at 250 degrees Celsius for 30minutes.